A battery performance test system and test method based on diamond nv color centers

Abstract

The application relates to a battery performance test system and a test method based on diamond NV color centers, and the test system comprises a battery test device and an NV color center detection device; the battery test device is used for electrochemical testing of a battery and regulating environmental variables such as a magnetic field, temperature, pressure and the like felt in the charging and discharging process of the battery; the NV color center detection device comprises a battery accommodating device, a light signal excitation device, a magnetic resonance regulating device and a light signal collection and processing device. Physical and chemical property changes caused by battery electrochemical reactions can affect the spin quantum state of the NV color center, and further cause changes in the NV fluorescence properties. By recording and analyzing the optically detected magnetic resonance signals of the NV color centers in or near the battery in the charging and discharging process, and combining the control of external field regulating parameters, the physical and chemical properties of the battery can be quantitatively obtained. The application can realize spatial resolution imaging of internal or adjacent parameters such as a magnetic field, temperature, pressure and the like of the battery, and monitor the time evolution process.

Description

Technical Field

[0001] This invention relates to the field of battery performance testing equipment technology, and in particular to a battery performance testing system and method based on diamond NV centers. Background Technology

[0002] Batteries are widely used in energy storage and power applications, and are extensively used in mobile phones, laptops, new energy vehicles, and other fields, becoming an indispensable part of people's lives. To ensure the safe, stable, and reliable operation of batteries, battery state monitoring has become a crucial issue. Electrochemical methods for testing voltage, current, capacity, and impedance are indirect testing methods, and many physical parameters, such as magnetic fields, cannot be detected electrochemically. Furthermore, traditional methods often characterize the overall properties of the battery; the test data includes various internal components such as the positive and negative electrode active materials, electrolyte, and current collectors, making it difficult to accurately characterize the physical properties of a specific component within the battery. Accurately understanding the state of a battery after cycling remains a challenge in the field of non-destructive testing. In-situ testing during battery cycling presents even greater challenges, but the information obtained is also more valuable. Developing a novel in-situ non-destructive testing technology is of great significance to the field of battery research.

[0003] Nitrogen-vacancy centers (NV centers) are atomic point defects commonly found in diamond. They possess excellent characteristics such as stable fluorescence intensity, small size, and long electron spin coherence time. Furthermore, they can operate under extremely wide temperature, pressure, and magnetic field conditions, including the complex liquid environments required for electrochemical testing. In recent years, diamond NV centers have been developed into a relatively mature quantum sensor, exhibiting unique advantages in the detection of magnetic fields, temperature, stress, voltage, and current, and are beginning to be widely applied in physics, chemistry, and biology. NV centers are obtained by artificially injecting nitrogen (N) to replace carbon atoms in the original crystal lattice of synthetic diamond, leaving a vacancy in an adjacent lattice to form a nitrogen-vacancy structure. NV centers can be considered as electrons with a spin quantum number of 1. When excited by light, they emit fluorescence, and their ground state is a spin triplet. Under resonant microwave modulation, electron spin resonance spectroscopy can be measured through the emitted fluorescence signal; this technique is called optically detected magnetic resonance (ODMR). The magnetic field near the NV center can cause clogging and splitting, thus affecting the frequency of microwave modulation. This property can be utilized to obtain the weak magnetic field near the NV center through optical magnetic resonance (OMR) measurements. Similarly, physical parameters sensed by the NV, such as temperature and stress, can also cause changes in the energy level difference between the ground triplet state, leading to changes in the microwave resonance frequency. This allows for the testing of other physical parameters near the NV center. Diamond NV centers have extremely small particle sizes, commonly ranging from atomic to micrometer scales, enabling detection with extremely high spatial resolution. Summary of the Invention

[0004] This invention provides a battery performance testing system and method based on diamond NV centers. In this testing system, based on NV center quantum sensing technology, an NV center detection device is combined with a battery testing device. The NV center is placed inside the battery's internal active material or outside the battery casing. Fluorescence is obtained by exciting the NV center with an optical signal excitation device of the NV center detection device. Simultaneously, the magnetic resonance modulation device of the NV center detection device outputs a known magnetic resonance modulation signal (at least one signal from radio frequency, microwave, or magnetic field) to the battery. At this time, the physicochemical properties of the battery's internal materials change, affecting the spin quantum state of the NV center, and thus altering the signal intensity of the NV fluorescence. The optical signal collection device of the NV center detection device then collects the change in the signal intensity of the NV fluorescence. The obtained NV fluorescence signal intensity, magnetic resonance modulation signal, and electrochemical test data are plotted and analyzed to characterize parameters such as magnetic field, temperature, stress, voltage, and electric field before and after battery cycling, accurately understanding the battery's state before and after cycling.

[0005] In a first aspect, embodiments of the present invention provide a battery performance testing system based on diamond NV centers, the testing system comprising: an NV center detection device and a battery testing device;

[0006] The NV color center detection device includes: a battery under test container, an optical signal excitation device, a magnetic resonance modulation device, and an optical signal collection device;

[0007] The battery holder is used to hold a battery containing NV color centers; the NV color centers are located in the active material of the battery or outside the battery casing.

[0008] The optical signal excitation device is used to emit a light source within a specific wavelength range to excite the NV color center and obtain NV fluorescence;

[0009] The magnetic resonance modulation device is used to output a magnetic resonance modulation signal; the magnetic resonance modulation device includes at least one of radio frequency equipment, microwave equipment, and magnetic field equipment; the magnetic resonance modulation signal includes at least one of radio frequency, microwave, or magnetic field signal.

[0010] Under the influence of the known magnetic resonance modulation signal output by the magnetic resonance modulation device, the physical and / or chemical properties of the active material or interfacial electrolyte of the battery change, affecting the spin quantum state of the NV color center, thereby changing the signal intensity of the NV fluorescence. The change value of the signal intensity of the NV fluorescence is collected by the optical signal collection device.

[0011] The battery testing device is used to perform electrochemical tests on the battery containing NV color centers, and to regulate and measure the environmental variables of the battery containing NV color centers during the charging and discharging process; the environmental variables include at least one of the following: magnetic field, temperature, and external pressure;

[0012] An analytical graph was plotted based on the signal intensity of the NV fluorescence, the magnetic resonance modulation signal, and the data from the electrochemical test.

[0013] Preferably, the battery testing device includes one or more of the following: a charge / discharge tester, an ambient magnetic field control and testing device, an external battery voltage application and testing device, and an ambient temperature control and testing device;

[0014] Preferably, the light source is a laser or a broadband light source with a wavelength below 637nm.

[0015] Preferably, when the NV color center is placed in the internal active material of the battery, the battery includes: a transparent battery casing, a positive electrode, a negative electrode, an electrolyte, a positive electrode tab, and a negative electrode tab; the positive electrode, the negative electrode, and the electrolyte are inside the transparent battery casing; the positive electrode tab and the negative electrode tab are respectively connected to the positive electrode and the negative electrode and extend to the outside of the transparent battery casing; the positive electrode and the negative electrode are insulated and isolated by an insulating carrier;

[0016] The transparent battery casing is made of quartz or plexiglass.

[0017] Preferably, when the NV color center is placed outside the battery casing, the battery is fixed in the pressure supply device;

[0018] The pressure-applying device is a transparent clamp used to fix the battery and apply a specific pressure to the battery;

[0019] The transparent clamp is made of quartz or plexiglass.

[0020] The diamond containing NV color centers includes any one of the following scales: atomic-level to 10nm scale, 10nm to 100μm scale, and scale greater than 100μm scale;

[0021] When the diamond containing NV color centers has a size of atomic-level - 10nm or 10nm-100μm, the NV color centers are placed in the internal active material of the battery;

[0022] When the NV color center is larger than 100 μm, the NV color center is placed outside the battery casing of the battery;

[0023] The optical signal collection device acquires the variation values ​​of NV fluorescence signal intensity under different magnetic resonance modulation signals at different diamond scales containing NV color centers.

[0024] Preferably, when the diamond containing NV color centers has a scale of atomic-level to 10 nm, the signal intensity of the NV fluorescence collected by the optical signal collection device is triggered by a change in at least one of the radio frequency, the microwave, or the magnetic field;

[0025] When the diamond containing NV color centers has a size of 10nm-100μm, the signal intensity of the NV fluorescence collected by the optical signal collection device is triggered by the change of the microwave and / or the magnetic field;

[0026] When the diamond containing the NV color center has a size greater than 100 μm, the signal intensity of the NV fluorescence collected by the optical signal collection device is triggered by a change in at least one of the radio frequency, the microwave, or the magnetic field.

[0027] Preferably, the analysis graph includes one or more of the following: optical magnetic resonance (ODMR), nuclear magnetic resonance (NMR), Ramsey probe sequence, or three-dimensional imaging mapping of physical quantities.

[0028] Secondly, embodiments of the present invention provide a testing method based on the battery performance testing system based on diamond NV centers described in the first aspect above, the testing method comprising:

[0029] Step S1: Connect the battery with NV color center in the NV color center detection device to the battery testing device; wherein, the NV color center is placed in the active material of the battery or outside the battery casing;

[0030] Step S2: Set the parameters of the optical signal excitation device, magnetic resonance modulation device, and optical signal collection device of the NV color center detection device;

[0031] Step S3: Turn on the battery testing device, optical signal excitation device, magnetic resonance modulation device and optical signal collection device. The optical signal excitation device emits a light source in a specific wavelength range to excite the NV color center to obtain NV fluorescence. At the same time, the battery testing device performs electrochemical testing on the battery.

[0032] Step S4: Under the influence of the known magnetic resonance modulation signal output by the magnetic resonance modulation device, the physical and / or chemical properties of the active material or interfacial electrolyte of the battery change, affecting the spin quantum state of the NV color center, thereby changing the signal intensity of NV fluorescence. The change value of the signal intensity of NV fluorescence is collected by the optical signal collection device.

[0033] Step S5: Draw an analysis graph based on the signal intensity of NV fluorescence, magnetic resonance modulation signal, and electrochemical test data.

[0034] Preferably, the electrochemical test includes at least one of the following: electric field, magnetic field, temperature, stress, and element type tests of the battery.

[0035] This invention provides a battery performance testing system and method based on diamond NV centers. In the testing system, a battery containing NV centers is first connected to a battery testing device for electrochemical testing. The NV centers are placed inside the battery's internal active material or outside the battery casing. The NV centers are excited by emitting a light source within a specific wavelength range through an optical signal excitation device to obtain NV fluorescence. Simultaneously, a magnetic resonance modulation device outputs a known magnetic resonance modulation signal (at least one signal of radio frequency, microwave, or magnetic field) to the NV centers. As the battery is charged and discharged, the physicochemical properties of the battery's active material or the interfacial electrolyte change, affecting the spin quantum state of the NV centers and thus altering the signal intensity of the NV fluorescence. The optical signal collection device then collects the change in the signal intensity of the NV fluorescence. The obtained NV fluorescence signal intensity, magnetic resonance modulation signal, and electrochemical test data are plotted and analyzed to characterize parameters such as magnetic field, temperature, stress, voltage, and electric field before and after battery cycling, providing a precise understanding of the battery's state before and after cycling.

[0036] This invention provides two battery performance testing systems based on diamond NV centers. The difference between these two systems lies in the NV center detection device. One system places the NV center within the active material inside the battery, while the other places it outside the battery. When the NV center is placed inside the active material, it exhibits extremely high spatial resolution. Because the NV center is in direct contact with the battery's active material, the accuracy of NV center detection of the battery's physicochemical properties is greatly improved. When the NV center is placed outside the battery, close to the battery's casing, no modification to the battery is required. This allows for the application of NV center quantum sensing technology in the battery's original, undamaged state, obtaining test data on the battery's physicochemical properties under undamaged conditions. This makes the technical solution widely applicable and capable of characterizing the physicochemical performance of all types of batteries.

[0037] The battery performance testing system based on diamond NV centers of this invention provides a quantitative analysis scheme for the detection of the physicochemical properties of batteries. The testing system has a simple structure, low cost, and can be used at room temperature. Attached Figure Description

[0038] The technical solutions of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples.

[0039] Figure 1 A structural block diagram of a battery performance testing system based on diamond NV centers provided in an embodiment of the present invention;

[0040] Figure 2 A flowchart of a battery performance testing system based on diamond NV centers provided in an embodiment of the present invention;

[0041] Figure 3 The physical property diagram of NV centers used in a battery performance testing system based on diamond NV centers provided in an embodiment of the present invention;

[0042] Figure 4 a is a schematic diagram of a battery performance testing system based on diamond NV centers provided in an embodiment of the present invention;

[0043] Figure 4 b is a basic schematic diagram of a battery performance testing system based on diamond NV color centers provided in an embodiment of the present invention;

[0044] Figure 4 c is a comparison diagram of three application scenarios of a battery performance testing system based on diamond NV centers provided in an embodiment of the present invention;

[0045] Figure 5 This is an example structural diagram of an NV center detection device in a battery performance testing system based on diamond NV centers provided in Embodiment 1 of the present invention.

[0046] Figure 6 This is an example structural diagram of the NV center detection device 2 in the battery performance testing system based on diamond NV centers provided in Embodiment 2 of the present invention;

[0047] Figure 7 The specific capacity-voltage curve of the battery under test during the discharge process provided in Embodiment 3 of the present invention;

[0048] Figure 8 This is a summary of the magnetic field characterization ODMR spectra of all discharge states of the battery under test provided in Embodiment 3 of the present invention. Detailed Implementation

[0049] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, it should be understood that these embodiments are only for more detailed description and should not be construed as limiting the present invention in any way, that is, not intended to limit the scope of protection of the present invention.

[0050] This invention provides a battery performance testing system based on diamond NV centers, such as... Figure 1 As shown in the structural block diagram, the test system includes: NV color center detection device 1 and battery testing device 2.

[0051] The NV color center detection device 1 includes: a battery under test container 11, an optical signal excitation device 12, a magnetic resonance modulation device 13, and an optical signal collection device 14.

[0052] Among them, the battery holder 11 is used to hold the battery containing NV color centers; the location of the NV color centers in the battery includes two cases: one is located in the internal active material, and the other is located outside the battery casing.

[0053] Specifically, the NV center is a diamond NV center, and the NV center contained in the diamond can be a single NV center or a cluster of NV centers; the scale of the diamond containing the NV center includes any one of the following: atomic-level to 10nm scale, 10nm-100μm scale, and larger than 100μm scale; when the scale is atomic-level to 10nm scale or 10nm-100μm scale, the NV center is placed in the internal active material of the battery; when the scale is larger than 100μm scale, the NV center is placed outside the battery casing.

[0054] The battery performance testing system based on diamond NV centers provided in this invention uses a wide range of diamond sizes containing NV centers, and the concentration range of NV centers in the diamonds used is also relatively wide. Furthermore, the experimental manipulation object can be selected as a single point NV center or a cluster of NV centers in the diamond according to different testing requirements. Therefore, it can realize micro-area magnetic resonance, internal battery testing, and external non-destructive testing of batteries based on NV center quantum technology.

[0055] The optical signal excitation device 12 is used to emit a light source within a specific wavelength range to excite NV color centers and obtain NV fluorescence; wherein, the light source within the specific wavelength range includes lasers or broadband light sources with wavelengths below 637nm, preferably lasers.

[0056] The magnetic resonance modulation device 13 is connected to the battery and is used to output a magnetic resonance modulation signal to the battery, including at least one of radio frequency, microwave or magnetic field; the magnetic resonance modulation device 13 includes at least one of radio frequency device 131, microwave device 132 and magnetic field device 133; the output terminal of the magnetic resonance modulation signal of the magnetic resonance modulation device 13 is close to the NV color center of the battery.

[0057] The optical signal collection device 14 is connected to the battery and is used to collect the change value of the NV fluorescence signal intensity. Specifically, under the action of the known magnetic resonance modulation signal output by the magnetic resonance modulation device 13, the physical and / or chemical properties of the internal active material or the interface electrolyte of the battery change, affecting the spin quantum state of the NV color center, thereby changing the signal intensity of the NV fluorescence. The change value of the NV fluorescence signal intensity is collected by the optical signal collection device 14.

[0058] The optical signal collection device 14 collects the changes in the signal intensity of NV fluorescence under different magnetic resonance modulation signals at different NV color centers.

[0059] Specifically, when the diamond containing NV centers has a size of atomic-level to 10 nm, the signal intensity of the NV fluorescence collected by the optical signal collection device 14 is triggered by a change in at least one of radio frequency, microwave, or magnetic field; when the diamond containing NV centers has a size of 10 nm to 100 μm, the signal intensity of the NV fluorescence collected by the optical signal collection device 14 is triggered by a change in microwave and / or magnetic field; when the diamond containing NV centers has a size greater than 100 μm, the signal intensity of the NV fluorescence collected by the optical signal collection device 14 is triggered by a change in at least one of radio frequency, microwave, or magnetic field.

[0060] The battery testing device 2 is connected to the battery containing the NV color center and is used to test the electrochemical performance of the battery. The battery testing device 2 includes one or more of the following devices: charge and discharge tester 21, environmental magnetic field control and testing equipment 22, external battery pressure and testing equipment 23, and environmental temperature control and testing equipment 24. It can test at least one of the following test items of the battery: electric field, magnetic field, temperature, and stress.

[0061] The above describes the various devices, their functions, and their connections in the battery performance testing system based on diamond NV centers provided in the embodiments of the present invention.

[0062] The following is based on Figure 2 The specific steps of the test method for characterizing the physical and chemical properties of the battery using the above test system will be explained. In the following sections, we will further explain the application of the specific device for two different battery positions of the NV color center in actual testing scenarios.

[0063] This invention provides a test method for characterizing the physicochemical properties of batteries using a battery performance testing system based on diamond NV centers, specifically comprising the following five steps:

[0064] Step S1: Connect the battery with the NV color center in the NV color center detection device to the battery testing device;

[0065] The NV color center is located in the active material of the battery or on the outside of the battery casing.

[0066] Step S2: Set the parameters of the optical signal excitation device, magnetic resonance modulation device, and optical signal collection device of the NV color center detection device.

[0067] Step S3: Turn on the battery testing device, optical signal excitation device, magnetic resonance modulation device and optical signal collection device. The optical signal excitation device emits a light source in a specific wavelength range to excite the NV color center to obtain NV fluorescence. At the same time, the battery testing device performs electrochemical testing on the battery.

[0068] Among them, the light source in a specific wavelength range includes broadband light sources with wavelengths below 637nm, preferably lasers.

[0069] Step S4: Under the influence of the known magnetic resonance modulation signal output by the magnetic resonance modulation device, the physical and / or chemical properties of the active material or interfacial electrolyte of the battery change, affecting the spin quantum state of the NV color center, thereby changing the signal intensity of NV fluorescence. The change value of the signal intensity of NV fluorescence is collected by the optical signal collection device.

[0070] Step S5: Draw an analysis graph based on the signal intensity of NV fluorescence, magnetic resonance modulation signal, and electrochemical test data;

[0071] The electrochemical test data includes at least one of the following: electric field, magnetic field, temperature, stress, and element type test data of the battery.

[0072] The analysis diagrams include one or more of the following: optical magnetic resonance (ODMR), nuclear magnetic resonance (NMR), Ramsey probe sequence, or three-dimensional imaging mapping of physical quantities.

[0073] The following is based on Figure 3 and Figure 4 The principle of the test method for characterizing the physicochemical properties of batteries using the above test system is explained.

[0074] The NV center used in this invention is composed of nitrogen atoms and their neighboring vacancies, which are obtained by artificially injecting them into the crystal material of diamond. In this invention, diamond NV centers are used. In optional schemes, other solid-state color center forms such as silicon carbide centers can also be used for battery performance characterization tests in the embodiments of this invention.

[0075] Taking diamond NV centers as an example, diamond NV centers can be obtained by artificially injecting a certain amount of N into synthetic diamond to replace the C atoms in the original crystal lattice and leaving a vacancy in the adjacent crystal lattice to form a nitrogen-vacancy structure.

[0076] Figure 3 The diagram shows the basic physical properties of the diamond NV color center. It can be seen that both the ground state and the excited state are determined by m... s Composed of triplet states of 0 or ±1, ground state m s =±1 and m s The energy level spacing of 0 is 2.87 GHz; typically, a 532 nm laser is used to excite the diamond NV color center. After electrons are excited from the ground state to the excited state, there are two transition pathways back to the ground state: radiative transition and non-radiative transition. The former emits fluorescence with a longer wavelength, while the latter does not emit fluorescence in the visible light band; initially, it is in m s Electrons with a =0 value typically undergo radiative transitions from m after excitation. s The excited state transitions back to m when the value is 0. s The ground state is 0, and it emits fluorescence; while initially it is in the m state.s Electrons of ±1 are excited to m s After reaching the excited state of ±1, it is more likely to pass through intersystem crossing via... 1 A1 and 1 The E level returns to the ground state, a process that does not emit fluorescence in the visible light spectrum. These two different pathways result in a significant difference in the fluorescence intensity collected by the light-collecting device; that is, the intensity of the fluorescence collected by the ground-state electron at the m level varies. s When m = 0, the excitation fluorescence intensity is high. s Fluorescence is weak when the value is ±1.

[0077] Before the test begins, the electron spin is polarized to m by laser irradiation for a certain period of time. s The ground state is 0, and then the ground state electrons m are excited by microwave, radio frequency, etc. s =0 to m s A change in fluorescence intensity can be observed with a transition of ±1; influenced by the physicochemical environment near the diamond NV color center, m s =±1 and m s The ground state spacing of 0 may change, and the originally degenerate energy level may also split, which in turn leads to changes in the frequency of ground state transitions excited by microwaves and radio frequencies. From this, the physicochemical parameters near the diamond NV color center can be analyzed.

[0078] Since the magnetic field near the NV center in diamond can induce Zeeman splitting and thus affect the NV resonance frequency, this property can be utilized to detect magnetic signals near the NV center using optically detected magnetic resonance (ODMR). Similarly, other physical parameters sensed by the NV, such as temperature and stress, can also cause changes in the energy level difference between the ground triplet state, leading to changes in the NV resonance frequency. This allows for the testing of other physical parameters near the NV center in this way.

[0079] In this embodiment of the invention, during battery charging and discharging, the valence states of the active material change, potentially transitioning from a state without magnetic moment to one with magnetic moment, or vice versa. The resulting local magnetic field induces Zeeman splitting changes in the nearby diamond NV color center, thus affecting the energy level difference between the ground state triplet. Corresponding information can be obtained from the ODMR spectrum to calculate the local magnetic field of the active material under different charging and discharging states. Simultaneously, battery charging and discharging may also cause phase changes in the active material, resulting in magnetic changes such as from subferrimagnetism to antiferromagnetism and then to ferromagnetism, significantly altering the magnetic field near the NV color center. Furthermore, the active material often expands during charging and discharging, causing significant changes in internal stress. Internal resistance also leads to thermal effects, altering the internal temperature. These changes in physical parameters affect the energy level difference between the ground state triplet, thereby changing the NV resonance frequency. Using this information, the corresponding physical parameters can be deduced.

[0080] Figure 4 a is a schematic diagram of the battery performance characterization test method based on NV color centers according to an embodiment of the present invention; Figure 4 b is a basic schematic diagram of the battery performance characterization based on the NV color center in an embodiment of the present invention. The signal to be tested (including mechanical, thermal, magnetic signals, etc.) will change the NV spin quantum state, thereby changing the NV fluorescence. The signal to be tested can be analyzed by the collected fluorescence signal and known magnetic resonance modulation factors (microwave, radio frequency, magnetic field, etc.), thereby obtaining the physicochemical properties near the NV color center. Figure 4 c is a comparison diagram of three application scenarios of battery performance characterization based on NV color centers in the embodiments of the present invention. Among them, diamond NV color centers can perform micro-area magnetic resonance on battery materials to obtain information such as the types of micro-elements and chemical environment. They can also be implanted inside the active materials of the battery to detect physical parameters such as magnetic field, temperature and stress in situ or in situ. Furthermore, they can be placed outside the battery to perform non-destructive testing on the battery.

[0081] This invention provides two battery performance testing systems based on diamond NV centers. The difference between these two systems lies in the NV center detection devices. In the first NV center detection device, the NV center is placed inside the active material of the battery, while in the second NV center detection device, the NV center is placed outside the battery, close to the battery packaging shell. To better understand the technical solution provided by this invention, the specific structures of the two NV center detection devices are described below with specific examples, and the specific process of applying these two NV center detection devices to the diamond NV center-based battery performance testing system to characterize battery performance is also explained.

[0082] Example 1

[0083] This example provides an NV center detection device 1, which places NV centers within the active material inside the battery. Its structural schematic diagram is shown below. Figure 5 As shown, it specifically includes: a transparent battery casing as a housing for the battery under test, a laser as an optical signal excitation device, an external microwave source and microwave antenna as a magnetic resonance modulation device, and an optical signal collection device (not shown in the figure).

[0084] The battery includes: a transparent battery casing, a positive electrode (not shown in the figure), a negative electrode (not shown in the figure), an electrolyte (not shown in the figure), a positive electrode tab, and a negative electrode tab; wherein, the positive electrode (not shown in the figure), the negative electrode (not shown in the figure), and the electrolyte (not shown in the figure) are inside the transparent battery casing, and an insulating carrier insulates and isolates the positive electrode from the negative electrode; the NV color center is placed inside the positive or negative electrode; the positive electrode tab and the negative electrode tab are respectively connected to the positive electrode and the negative electrode and extend to the outside of the transparent battery casing, and the positive electrode tab and the negative electrode tab are used to connect to battery testing equipment, such as an external circuit charge and discharge tester; the transparent battery casing is made of quartz or plexiglass and is transparent to laser light.

[0085] A laser is used as an optical signal excitation device to emit a laser of a specific wavelength to excite the NV color center of diamond, thereby obtaining NV fluorescence.

[0086] An external microwave source and microwave antenna are used as magnetic resonance modulation devices to output microwave magnetic resonance modulation signals to the NV color center, with the microwave antenna placed close to the diamond NV color center.

[0087] The optical signal collection device (not shown in the figure) is used to collect the change value of the signal intensity of NV fluorescence. Specifically, under the action of the known laser magnetic resonance modulation signal output by the external microwave source, the physical and / or chemical properties of the internal active material or the interfacial electrolyte of the battery change, affecting the spin quantum state of the diamond NV color center, thereby changing the signal intensity of NV fluorescence. The change value of the signal intensity of NV fluorescence is collected by the optical signal collection device.

[0088] By collecting fluorescence signals and known microwave magnetic resonance modulation signals, mechanical, thermal, and magnetic parameters can be calculated to obtain information on the physicochemical properties near the NV color center.

[0089] The NV color center detection device provided in this example, because the NV color center is placed in the active material of the battery and the microwave antenna is also placed close to the NV color center, is fully integrated inside the battery, which can maximize the signal processing accuracy and spatial resolution.

[0090] Example 2

[0091] This example provides an NV center detection device II with the NV center located outside the battery and close to the battery package shell. Its structural schematic diagram is shown below. Figure 6 As shown, it specifically includes: a transparent clamp, a laser as an optical signal excitation device, an external microwave source and a microwave antenna as a magnetic resonance modulation device, and an optical signal collection device (not shown in the figure).

[0092] The battery is a pouch cell, with the diamond NV color center closely attached to the battery's encapsulation shell.

[0093] The transparent clamp is used to fix the battery and can apply a specific pressure to the battery, allowing it to charge and discharge under a specific pressure working environment; the transparent clamp is made of quartz or plexiglass and is transparent to laser light.

[0094] A laser is used as an optical signal excitation device to emit a laser of a specific wavelength to excite the NV color center of diamond, thereby obtaining NV fluorescence.

[0095] An external microwave source and microwave antenna are used as magnetic resonance modulation devices to output microwave magnetic resonance modulation signals to the NV color center, with the microwave antenna placed close to the diamond NV color center.

[0096] The optical signal collection device (not shown in the figure) is used to collect the change value of the signal intensity of NV fluorescence. Specifically, under the action of the known laser magnetic resonance modulation signal output by the external microwave source, the physical and / or chemical properties of the internal active material or the interfacial electrolyte of the battery change, affecting the spin quantum state of the diamond NV color center, thereby changing the signal intensity of NV fluorescence. The change value of the signal intensity of NV fluorescence is collected by the optical signal collection device.

[0097] By collecting fluorescence signals and known microwave magnetic resonance modulation signals, mechanical, thermal, and magnetic parameters can be calculated to obtain information on the physicochemical properties near the NV color center.

[0098] The NV center detection device II provided in this example, since the diamond NV center and microwave antenna are placed outside the battery, can be used without any testing or modification of the battery. Therefore, it can perform non-destructive characterization on a large number of different types of commercial batteries, greatly improving its versatility. At the same time, the pressure device maximizes the reproduction of the battery's working environment, making the data more practical.

[0099] Example 3

[0100] The NV center detection device provided in Example 1 is used in conjunction with a battery testing device to form a battery performance testing system based on diamond NV centers. The system then performs magnetic field characterization on batteries containing NV centers. The specific process is as follows:

[0101] (1) Battery manufacturing process:

[0102] The preparation of the positive electrode material and the positive electrode sheet is as follows: The positive electrode material is iron(III) oxide (Fe3O4). The positive electrode active material, Fe3O4, the conductive additive carbon black, and the polyvinylidene fluoride (PVDF) binder are weighed according to a mass ratio of 8:1:1, wherein the PVDF exists in the form of a solution of N-methylpyrrolidone (NMP). After the active material and conductive additive are thoroughly ground, the PVDF is added, and the mixture is mixed uniformly at high speed in a mixer. The slurry is then uniformly coated onto copper foil. After complete drying, the electrode sheet is obtained using a slicing machine. Diamond NV color centers are ultrasonically dissolved in alcohol, then uniformly sprinkled onto the electrode sheet and dried to obtain the positive electrode sheet.

[0103] The negative electrode is made of lithium.

[0104] The electrolyte used was 1M LiPF6, and the solvent was ethylene carbonate EC and dimethyl carbonate DMC in a mass ratio of 1:1.

[0105] The above-mentioned positive and negative electrode sheets are insulated and isolated by an insulating carrier, and then assembled with electrolyte, positive electrode tab, negative electrode tab and transparent battery shell to form the battery to be tested.

[0106] (2) Magnetic field characterization of batteries containing diamond NV centers, test steps:

[0107] Step S1: Connect the positive and negative tabs of the battery under test in the NV color center detection device to the charge-discharge tester, set the test parameters, use constant current charge-discharge test, rate 0.2C, discharge voltage range from open circuit voltage to 0V; wherein, the scale of the diamond NV color center is 1μm.

[0108] Step S2: Set the parameters of the magnetic resonance modulation device and the light source wavelength of the laser according to the test requirements.

[0109] Step S3: Use microwaves to sweep the ODMR spectrum at the initial position.

[0110] Step S4: Discharge the battery for 7 minutes and record the ODMR spectrum at this time.

[0111] Step S5: Discharge the battery for 14 minutes and record the ODMR spectrum at this time.

[0112] Step S6: Discharge the battery for 21 minutes and record the ODMR spectrum at this time.

[0113] Step S7: Discharge the battery for 28 minutes and record the ODMR spectrum at this time.

[0114] Step S8: Discharge the battery for 48 minutes and record the ODMR spectrum at this time.

[0115] Step S9: Fully discharge the battery until it reaches 0V, and record the ODMR spectrum at this point.

[0116] Step S10: Draw ODMR spectrum based on microwave frequency and fluorescence intensity to calculate the energy level spacing of ground state |±1>, and then calculate the magnetic field strength of the battery active material iron(III) oxide near the NV color center during the charging and discharging process.

[0117] Figure 7 The specific capacity-voltage curve of the battery under test provided in Example 3 shows the discharge process. The left vertical axis is voltage (V) and the horizontal axis is specific capacity (mAh / g). The position of charge and discharge degree during 7 in-situ tests is marked in the figure.

[0118] Figure 8This is a summary of the magnetic field characterization ODMR spectra of the battery under test in all discharge states provided in Example 3. From top to bottom, the ODMR spectra represent the seven stages of the battery under test from the initial state to the fully discharged state. The left vertical axis represents the normalized relative fluorescence intensity (Norm.PL, ab.units), and the horizontal axis represents the microwave frequency (MW, GHz). The iron(III) oxide near the NV color center is magnetized by the applied magnetic field in the initial state, exhibiting significant magnetism and a clearly split ODMR spectrum. However, after the start of discharge, the ODMR spectrum splitting gradually narrows, indicating that as the discharge progresses, the iron(III) oxide is continuously reduced to ferrous oxide, and the overall magnetism continuously decreases. At 14 minutes of the second discharge, the magnetic field strength sensed by the NV decreases from 66.3 Gs in the initial state to 43.3 Gs. The magnetic field strength in the third and fourth discharges does not decrease significantly and remains almost unchanged, indicating that the active material bulk phase at this stage... The initial discharge phase was dominated by ferrous oxide. As the discharge duration increased to 48 minutes, the magnetic field strength sensed by NV rose to 53.0 Gs, indicating that ferrous oxide was continuously reduced to ferromagnetic iron during this phase. The magnetization under the external magnetic field enhanced the combined magnetic field, resulting in greater energy level splitting at the NV color center. When the discharge reached 0V, the combined magnetic field under the external magnetic field reached a maximum value of 93.6 Gs, far exceeding the combined magnetic field strength of the initially magnetized magnetite, indicating that almost all of the ferrous oxide was reduced to iron.

[0119] This embodiment demonstrates the possibility of combining a battery performance testing system based on diamond NV centers with a battery system, and can realize the detection of physical parameters of active materials inside the battery through NV centers during battery charging and discharging, and verify the phase changes during battery charging and discharging.

[0120] Example 4

[0121] The NV center detection device II provided in Example 2 is used in conjunction with the battery testing device to form a battery performance testing system based on diamond NV centers. The battery magnetic field is characterized for batteries containing NV centers. The specific process is as follows:

[0122] (1) Fixing the battery under test: The battery is a common lithium cobalt oxide-graphite battery. Diamond NV color centers are sprinkled on the outside of the battery shell. The microwave antenna is placed close to the diamond NV color centers. The battery, microwave antenna and diamond NV color centers are fixed with transparent clamps and pressure is applied at the same time. The diamond NV color centers have a scale of 100μm.

[0123] (2) Characterize the battery under test with a magnetic field. Test steps:

[0124] Step S1: Connect the battery under test in the NV color center detection device 2 to the charge-discharge tester, set the test parameters, use constant current charge-discharge test, rate 1C, voltage range 4.35V-3V, cycle number 1000 cycles.

[0125] Step S2: Set the external magnetic field and the laser light source wavelength according to the test requirements.

[0126] Step S3: Use microwave to perform frequency sweep and start recording the ODMR spectrum.

[0127] Step S4: Begin the 1000-cycle charge-discharge test.

[0128] Step S5: Based on the real-time ODMR spectral analysis of the AC magnetic susceptibility distribution, the possible failure time of the battery and the growth location of lithium dendrites are inferred.

[0129] Example 5

[0130] The NV center detection device II provided in Example 2 is used in conjunction with the battery testing device to form a battery performance testing system based on diamond NV centers. Micro-area magnetic resonance testing is then performed on batteries containing NV centers. The specific process is as follows:

[0131] Step S1: Connect the battery to a charge / discharge tester and cycle it to a specific number of cycles or a specific charge / discharge state. The battery used is a common lithium cobalt oxide-graphite battery.

[0132] Step S2 involves disassembling the lithium cobalt oxide-graphite battery after the cycle in step S1 to obtain a positive electrode and a negative electrode. Diamond NV color centers are sprinkled into the lithium cobalt oxide of the positive electrode, wherein the size of the diamond NV color centers is 10nm.

[0133] Step S3: Place the positive electrode containing the diamond NV color center on the transparent clamp of the test system, and set the external magnetic field and the laser light source wavelength according to the test requirements.

[0134] Step S4: Laser excitation of diamond NV color centers to obtain NV fluorescence. Simultaneously, microwave, radio frequency, or magnetic field signals output by magnetic resonance modulation equipment are used for frequency sweeping. The NV fluorescence changes with the microwave, radio frequency, or magnetic field signals, and NMR spectrum recording begins.

[0135] Step S5: Based on NMR spectroscopy analysis of the chemical environment and element types near the diamond NV color center of the positive electrode sheet, the battery is characterized mechanistically.

[0136] This invention provides a battery performance testing system and method based on diamond NV centers. In the testing system of this invention, a battery containing NV centers is first connected to a battery testing device for electrochemical testing. The NV centers are placed inside the active material of the battery or outside the battery casing. The NV centers are excited by emitting a light source within a specific wavelength range through an optical signal excitation device to obtain NV fluorescence. At the same time, a magnetic resonance modulation device outputs a known magnetic resonance modulation signal (at least one signal of radio frequency, microwave, or magnetic field) to the battery. At this time, the physicochemical properties of the active material or interfacial electrolyte of the battery change, affecting the spin quantum state of the NV centers, thereby changing the signal intensity of the NV fluorescence. The optical signal collection device then collects the change value of the NV fluorescence signal intensity. The obtained NV fluorescence signal intensity, magnetic resonance modulation signal, and electrochemical test data are plotted and analyzed to analyze and characterize parameters such as magnetic field, temperature, stress, voltage, and current before and after battery cycling, so as to accurately understand the state of the battery before and after cycling.

[0137] This invention provides two battery performance testing systems based on diamond NV centers. The difference between these two systems lies in the NV center detection device. One system places the NV center within the active material inside the battery, while the other places it outside the battery. When the NV center is placed inside the active material, it exhibits extremely high spatial resolution. Because the NV center is in direct contact with the battery's active material, the accuracy of NV center detection of the battery's physicochemical properties is greatly improved. When the NV center is placed outside the battery, close to the battery's casing, no modification to the battery is required. This allows for the application of NV center quantum sensing technology in the battery's original, undamaged state, obtaining test data on the battery's physicochemical properties under undamaged conditions. This makes the technical solution widely applicable and capable of characterizing the physicochemical performance of all types of batteries.

[0138] The battery performance testing system based on diamond NV centers of this invention provides a quantitative analysis scheme for the detection of the physicochemical properties of batteries. The testing system has a simple structure, low cost, and can be used at room temperature.

[0139] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A battery performance testing system based on diamond NV centers, characterized in that, The testing system includes: a battery testing device and an NV color center detection device; The NV color center detection device includes: a battery under test container, an optical signal excitation device, a magnetic resonance modulation device, and an optical signal collection and signal processing device; The battery holder is used to hold a battery containing NV color centers; the NV color centers are located in the active material of the battery or outside the battery casing. The optical signal excitation device is used to emit a light source within a specific wavelength range to excite the NV color center and obtain NV fluorescence; The magnetic resonance modulation device is used to output a magnetic resonance modulation signal; the magnetic resonance modulation device includes at least one of radio frequency equipment, microwave equipment, and magnetic field equipment; the magnetic resonance modulation signal includes at least one of radio frequency, microwave, or magnetic field signal. Under the influence of the known magnetic resonance modulation signal output by the magnetic resonance modulation device, the physical and / or chemical properties of the active material or interfacial electrolyte of the battery change, affecting the spin quantum state of the diamond NV center, thereby changing the signal intensity of the NV center fluorescence. The change in the signal intensity of the NV fluorescence is collected by the optical signal collection device. The battery testing device is used to perform electrochemical tests on the battery containing NV color centers, and to regulate and measure the environmental variables of the battery containing NV color centers during the charging and discharging process; the environmental variables include at least one of the following: magnetic field, temperature, and pressure. Analytical graphs were plotted based on the signal intensity of the NV fluorescence, the magnetic resonance modulation signal, the environmental variables, and the data from the electrochemical tests.

2. The battery performance testing system based on diamond NV centers according to claim 1, characterized in that, The battery testing device includes one or more of the following: a charge / discharge tester, an environmental magnetic field control and testing device, an external battery pressure testing device, and an environmental temperature control and testing device.

3. The battery performance testing system based on diamond NV centers according to claim 1, characterized in that, The light source includes lasers or broadband light sources with wavelengths below 637 nm.

4. The battery performance characterization and testing system based on diamond NV centers according to claim 1, characterized in that, When the NV color center is placed in the internal active material of the battery, the battery includes: a transparent battery casing, a positive electrode, a negative electrode, an electrolyte, a positive electrode tab, and a negative electrode tab; the positive electrode, the negative electrode, and the electrolyte are inside the transparent battery casing; the positive electrode tab and the negative electrode tab are respectively connected to the positive electrode and the negative electrode and extend to the outside of the transparent battery casing; the positive electrode and the negative electrode are insulated and isolated by an insulating carrier; The transparent battery casing is made of quartz or plexiglass.

5. The battery performance testing system based on diamond NV centers according to claim 1, characterized in that, When the NV color center is placed outside the battery casing, the battery is fixed in the pressure application device; the pressure application device is a transparent clamp used to fix the battery and apply a specific pressure to the battery; The transparent clamp is made of quartz or plexiglass.

6. The battery performance testing system based on diamond NV centers according to claim 1, characterized in that, The NV color center is a diamond NV color center; The diamond contains either a single NV color center or a cluster of NV color centers. The diamond containing NV color centers includes any one of the following scales: atomic-level to 10nm scale, 10nm to 100μm scale, and scale greater than 100μm scale; When the diamond containing NV color centers has a size of atomic-level - 10nm or 10nm-100μm, the NV color centers are placed in the internal active material of the battery; When the size of the diamond containing the NV color center is greater than 100 μm, the NV color center is placed outside the battery casing of the battery; The optical signal collection device acquires the variation values ​​of NV fluorescence signal intensity under different magnetic resonance modulation signals at different diamond scales containing NV color centers.

7. The battery performance testing system based on diamond NV centers according to claim 6, characterized in that, When the diamond containing NV color centers has a scale of atomic-level -10nm, the signal intensity of the NV fluorescence collected by the optical signal collection device is triggered by a change in at least one of the radio frequency, the microwave, or the magnetic field; When the diamond containing NV color centers has a size of 10nm-100μm, the signal intensity of the NV fluorescence collected by the optical signal collection device is triggered by the change of the microwave and / or the magnetic field; When the diamond containing the NV color center has a size greater than 100 μm, the signal intensity of the NV fluorescence collected by the optical signal collection device is triggered by a change in at least one of the radio frequency, the microwave, or the magnetic field.

8. The battery performance testing system based on diamond NV centers according to claim 1, characterized in that, The analysis graphs include one or more of the following: optical magnetic resonance (ODMR), nuclear magnetic resonance (NMR), Ramsey detector sequences, or three-dimensional imaging mapping of physical quantities.

9. A test method for a battery performance testing system based on diamond NV centers as described in any one of claims 1-8, characterized in that, The testing method includes: Step S1: Connect the battery with NV color center in the NV color center detection device to the battery testing device; wherein, the NV color center is placed in the active material of the battery or outside the battery casing; Step S2: Set the parameters of the optical signal excitation device, magnetic resonance modulation device, and optical signal collection device of the NV color center detection device; Step S3: Turn on the battery testing device, optical signal excitation device, magnetic resonance modulation device and optical signal collection device. The optical signal excitation device emits a light source in a specific wavelength range to excite the NV color center to obtain NV fluorescence. At the same time, the battery testing device performs electrochemical testing on the battery. Step S4: Under the influence of the known magnetic resonance modulation signal output by the magnetic resonance modulation device, the physical and / or chemical properties of the active material or interfacial electrolyte of the battery change, affecting the spin quantum state of the NV color center, thereby changing the signal intensity of NV fluorescence. The change value of the signal intensity of NV fluorescence is collected by the optical signal collection device. Step S5: Draw an analysis graph based on the signal intensity of NV fluorescence, magnetic resonance modulation signal, and electrochemical test data.

10. The test method according to claim 9, characterized in that, The electrochemical tests include at least one of the following: electric field, magnetic field, temperature, stress, and element type tests of the battery.

Images